I bought a set of Taylor wires from my local Indy. It was a Universal kit that I cut to the length that I wanted them to be. If you check out J&P cycles they sell model specific Taylor kits (if your coil is in the stock position). They are much thicker and a much better design than anything the Harley dealer will have. Other brands that would be good would be MSD and NGK.
If your engine is not modified (ie. stage 3) your wasting your money. The stock wires are more than adequate for the amount of energy required. If you want improved spark, buy a set of Iridium plugs. They'll set you back about $15. You will notice an increase in throttle response.